Extending the reach of wireless communication is a challenge for all types of network, especially in the rural or remote areas. Due to the nature of the radio environment, services and power are difficult to deliver. It is both impractical and uneconomical to deliver coverage using a traditional base station approach. Taking LTE for example, it will be deployed at higher carrier frequencies than existing 2G and 3G systems, which implies higher propagation losses for LTE and potentially a need to add more sites to ensure sufficiently good coverage. Adding sites is costly and requires lengthy negotiations. Machine-to-Machine (M2M) applications required low-cost devices and improved coverage other than the current cellular communication system. For example, some smart metering deceives are often installed in the basements of residential buildings or locations shielded by foil-backed insulation, metalized windows, or traditional thick-walled building construction. These smart devices suffer a significantly larger path-loss, such as 20 dB path loss, than that in the typical operation condition of normal devices. In order to ensure the network provides the best possible solutions to maximize coverage and serves the specific devices, the 3rd generation partnership project (3GPP) RAN1 working group has studied for coverage improvement for devices requiring coverage extension/coverage enhancement (CE). Some potential solutions have been identified such as repetition of the physical channels to improve the coverage.
For network-originated data transfer to UEs requiring CE, some challenges are expected when they are in RRC_IDLE, which include the network does not know which cell the UE camps on, and whether the UE requires CE or not. Therefore, the network would not know whether to page the UE with CE through transmission repetitions. One possible solution is that on the network side, the MME assumes the UE does not require CE. The network pages the UE normally without requiring the knowledge of the UE CE status. However, under this approach since there is no HARQ process for paging, the UE requiring CE normally cannot receive the paging message in one paging occasion, which means the UE is unreachable.
Improvement and enhancement are required to efficiently paging the UEs requiring CE in the wireless network.